1. Field of the Invention
The present invention relates to an apparatus for feeding stock material intermittently to a press, such as those used for stamping or drawing.
2. Description of the Related Art
There are numerous types of press feed mechanisms available, each exhibiting a set of strength and weaknesses depending upon the specific application. For instance, a cam-feed type mechanism having high performance characteristics means usually foregoing flexibility such as with a servo-type machine. A servo-type press feed mechanism has an increased ease of set-up, but may sacrifice speed as offered by a cam-feed mechanism.
New high speed electronic roll feed mechanisms provide both smooth velocity profiles and high speed characteristics with flexibility. Prior cam, servo, and high speed electronic feed devices utilize different arrangements for providing the ability to provide clean and accurate lifting of the pinch roll. The pinch roll moves from a maximum clamping and contacting position against the stock, to a position away and out of contact with the stock material, thus creating what is termed roll lift. This roll lift requirement, if not accurate, and in time with roller release can prohibit proper die pilot pin operation. Furthermore, these devices need to permit accurate pinch roll return to a contact position with the material in a controlled manner. Slamming of the pinch or pressure roll into the material can cause the roll to bounce or, alternatively, deform the material.
Typical press feed mechanisms have utilized roll lift in which the feed has a pinch roll that moves out of contact with the stock so that the press can control stock by the use of pilot pins and align the stock within the press. In other words, the pinch roll loses physical contact with the stock for a particular time during the feeding cycle. This prior system was utilized to eliminate any placement error that was left over from the feed progression.
Known feed system also includes a gear train that increases the rotational inertia of the system.
What is needed in the art is the ability to more accurately control the stocks at high speed by using a higher speed roll lift method.